| Abstract
| - A series of mono- and binuclear aryldiazene complexes of the types [Re(ArNNH)(CO)5-nPn]BY4 and [{Re(CO)5-nPn}2(μ-HNNAr−ArNNH)](BY4)2 (P = phosphite) were prepared. Unprecedented “diazene−diazonium” derivatives of the type [M(CO)3P2(HNNAr−ArN⋮N)](BY4)2 (M = Re, Mn) were also obtained and used in the syntheses of the first heterobinuclear complexes [M1]−μ-HNNAr−ArNNH−[M2] containing bis(aryldiazene) bridging ligands. The binuclear complexes [M1]−μ-N2Ar−ArN2−[M2] with bis(aryldiazenido) bridging ligands were also prepared.
- The mono- and binuclear aryldiazene complexes [Re(C6H5NNH)(CO)5-nPn]BY4 (1−5) and [{Re(CO)5-nPn}2(μ-HNNAr−ArNNH)](BY4)2 (6−12) [P = P(OEt)3, PPh(OEt)2, PPh2OEt; n = 1−4; Ar−Ar = 4,4‘-C6H4−C6H4, 4,4‘-(2-CH3)C6H3−C6H3(2-CH3), 4,4‘-C6H4−CH2−C6H4; Y = F, Ph) were prepared by reacting the hydridespecies ReH(CO)5-nPn with the appropriate mono- and bis(aryldiazonium) cations. These compounds, as well asother prepared compounds, were characterized spectroscopically (IR; 1H, 31P, 13C, and 15N NMR data), and 1awas also characterized by an X-ray crystal structure determination. [Re(C6H5NNH)(CO){P(OEt)3}4]BPh4 (1a)crystallizes in space group P1̄ with a = 15.380(5) Å, b = 13.037(5) Å, c = 16.649(5) Å, α = 90.33(5)°, β =91.2(1)°, γ = 89.71(9)°, and Z = 2. The “diazene−diazonium” complexes [M(CO)3P2(HNNAr−ArN⋮N)](BF4)2 (13−15, 17) [M = Re, Mn; P = PPh2OEt, PPh2OMe, PPh3; Ar−Ar = 4,4‘-C6H4−C6H4, 4,4‘-C6H4−CH2−C6H4] and [Re(CO)4(PPh2OEt)(4,4‘-HNNC6H4−C6H4N⋮N)](BF4)2 (16b) were synthesized by allowingthe hydrides MH(CO)3P2 or ReH(CO)4P to react with equimolar amounts of bis(aryldiazonium) cations underappropriate conditions. Reactions of diazene−diazonium complexes 13−17 with the metal hydrides M2H2P‘4and M2‘H(CO)5-nP‘ ‘n afforded the heterobinuclear bis(aryldiazene) derivatives [M1(CO)3P2(μ-HNNAr−ArNNH)M2HP‘4](BPh4)2 (ReFe, ReRu, ReOs, MnRu, MnOs) and [M1(CO)3P2(μ-HNNAr−ArNNH)M2‘(CO)5-nP‘ ‘n](BPh4)2 (ReMn, MnRe) [M1 = Re, Mn; M2 = Fe, Ru, Os; M2‘ = Mn, Re; P = PPh2OEt, PPh2OMe;P‘, P‘ ‘ = P(OEt)3, PPh(OEt)2; Ar−Ar = 4,4‘-C6H4−C6H4, 4,4‘-C6H4−CH2−C6H4; n = 1, 2]. The heterotrinuclearcomplexes [Re(CO)3(PPh2OEt)2(μ-4,4‘-HNNC6H4−C6H4NNH)M{P(OEt)3}4(μ-4,4‘-HNNC6H4−C6H4NNH)Mn(CO)3(PPh2OEt)2](BPh4)4 (M = Ru, Os) (ReRuMn, ReOsMn) were obtained by reacting the heterobinuclear complexes ReRu and ReOs with the appropriate diazene−diazonium cations. The heterobinuclear complexwith a bis(aryldiazenido) bridging ligand [Mn(CO)2(PPh2OEt)2(μ-4,4‘-N2C6H4−C6H4N2)Fe{P(OEt)3}4]BPh4 (MnFe)was prepared by deprotonating the bis(aryldiazene) compound [Mn(CO)3(PPh2OEt)2(μ-4,4‘-HNNC6H4−C6H4NNH)Fe(4-CH3C6H4CN){P(OEt)3}4](BPh4)3. Finally, the binuclear compound [Re(CO)3(PPh2OEt)2(μ-4,4‘-HNNC6H4−C6H4N2)Fe(CO)2{P(OPh)3}2](BPh4)2 (ReFe) containing a diazene−diazenido bridging ligand was preparedby reacting [Re(CO)3(PPh2OEt)2(4,4‘-HNNC6H4−C6H4N⋮N)]+ with the FeH2(CO)2{P(OPh)3}2 hydride derivative. The electrochemical reduction of mono- and binuclear aryldiazene complexes of both rhenium (1−12) andthe manganese, as well as heterobinuclear ReRu and MnRu complexes, was studied by means of cyclicvoltammetry and digital simulation techniques. The electrochemical oxidation of the mono- and binucleararyldiazenido compounds Mn(C6H5N2)(CO)2P2 and {Mn(CO)2P2}2(μ-4,4‘-N2C6H4−C6H4N2) (P = PPh2OEt) wasalso examined. Electrochemical data show that, for binuclear compounds, the diazene bridging unit allowsdelocalization of electrons between the two different redox centers of the same molecule, whereas the two metalcenters behave independently in the presence of the diazenido bridging unit.
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